Package org.jcsp.util.ints
Class OverWriteOldestBufferInt
- java.lang.Object
-
- org.jcsp.util.ints.OverWriteOldestBufferInt
-
- All Implemented Interfaces:
java.io.Serializable
,java.lang.Cloneable
,ChannelDataStoreInt
public class OverWriteOldestBufferInt extends java.lang.Object implements ChannelDataStoreInt, java.io.Serializable
This is used to create a buffered integer channel that always accepts input, overwriting its oldest data if full.Description
OverWriteOldestBufferInt is an implementation of ChannelDataStoreInt that yields a FIFO buffered semantics for a channel. When empty, the channel blocks readers. When full, a writer will overwrite the oldest item left unread in the channel. See the static construction methods ofChannel
(Channel.one2oneInt(org.jcsp.util.ints.ChannelDataStoreInt)
etc.).The getState method returns EMPTY or NONEMPTYFULL, but never FULL.
- Author:
- P.D. Austin
- See Also:
ZeroBufferInt
,BufferInt
,OverWritingBufferInt
,OverFlowingBufferInt
,InfiniteBufferInt
,ChannelInt
, Serialized Form
-
-
Field Summary
-
Fields inherited from interface org.jcsp.util.ints.ChannelDataStoreInt
EMPTY, FULL, NONEMPTYFULL
-
-
Constructor Summary
Constructors Constructor Description OverWriteOldestBufferInt(int size)
Construct a new OverWriteOldestBufferInt with the specified size.
-
Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description java.lang.Object
clone()
Returns a new (and EMPTY) OverWriteOldestBufferInt with the same creation parameters as this one.void
endGet()
SeestartGet()
for a description of the semantics of this method.int
get()
Returns the oldest int from the OverWriteOldestBufferInt and removes it.int
getState()
Returns the current state of the OverWriteOldestBufferInt.void
put(int value)
Puts a new int into the OverWriteOldestBufferInt.void
removeAll()
int
startGet()
Begins an extended rendezvous by the reader.
-
-
-
Constructor Detail
-
OverWriteOldestBufferInt
public OverWriteOldestBufferInt(int size)
Construct a new OverWriteOldestBufferInt with the specified size.- Parameters:
size
- the number of ints the OverWriteOldestBufferInt can store.- Throws:
BufferIntSizeError
- if size is zero or negative. Note: no action should be taken to try/catch this exception - application code generating it is in error and needs correcting.
-
-
Method Detail
-
get
public int get()
Returns the oldest int from the OverWriteOldestBufferInt and removes it.Pre-condition: getState must not currently return EMPTY.
- Specified by:
get
in interfaceChannelDataStoreInt
- Returns:
- the oldest int from the OverWriteOldestBufferInt
-
startGet
public int startGet()
Begins an extended rendezvous by the reader. The semantics of an extended rendezvous on an overwrite-oldest buffer are slightly complicated, but hopefully intuitive. When a reader begins an extended rendezvous, the oldest value is returned from the buffer (as it would be for a call toget()
). While an extended rendezvous is ongoing, the writer may (repeatedly) write to the buffer, without ever blocking. When the reader finishes an extended rendezvous, the following options are possible:- The writer has not written to the channel during the rendezvous. In this case, the value that was read at the start of the rendezvous is removed from the buffer.
- The writer has written to the channel during the rendezvous, but has not over-written the value that was read at the start of the rendezvous. In this case, the value that was read at the start of the rendezvous is removed from the buffer.
- The writer has written to the channel during the rendezvous, and has over-written (perhaps repeatedly) the value that was read at the start of the rendezvous. In this case, the value that was read at the start of the rendezvous is no longer in the buffer, and hence nothing is removed.
- Specified by:
startGet
in interfaceChannelDataStoreInt
- Returns:
- The oldest value in the buffer at this time
- See Also:
ChannelDataStoreInt.endGet()
-
endGet
public void endGet()
SeestartGet()
for a description of the semantics of this method.- Specified by:
endGet
in interfaceChannelDataStoreInt
- See Also:
ChannelDataStoreInt.startGet()
-
put
public void put(int value)
Puts a new int into the OverWriteOldestBufferInt.If OverWriteOldestBufferInt is full, the oldest item left unread in the buffer will be overwritten.
- Specified by:
put
in interfaceChannelDataStoreInt
- Parameters:
value
- the int to put into the OverWriteOldestBufferInt
-
getState
public int getState()
Returns the current state of the OverWriteOldestBufferInt.- Specified by:
getState
in interfaceChannelDataStoreInt
- Returns:
- the current state of the OverWriteOldestBufferInt (EMPTY or NONEMPTYFULL)
-
clone
public java.lang.Object clone()
Returns a new (and EMPTY) OverWriteOldestBufferInt with the same creation parameters as this one.Note: Only the size and structure of the OverWriteOldestBufferInt is cloned, not any stored data.
- Specified by:
clone
in interfaceChannelDataStoreInt
- Overrides:
clone
in classjava.lang.Object
- Returns:
- the cloned instance of this OverWriteOldestBufferInt.
-
removeAll
public void removeAll()
- Specified by:
removeAll
in interfaceChannelDataStoreInt
-
-